POJ 2777 Count Color 线段树

/**
* @file main.cpp
* @brief 线段树,注意几点:
*        1.输入数据中有可能有a>b的情况,需要做特殊处理
*        2.cin会超时,使用scanf
*        3.线段树染色/插入的时候注意
*            如果待插入区间等于线段树区间,直接插入
*            递归处理子区间之前,需要把父亲节点的染色(如果有的话)传递给左右两个子节点,同时清除父亲节点的染色
*        4.使用位运算会使得代码更清爽
*
* @author yekeren
* @version 1.0.0
* @date 2013-06-09
*/
#include <stdio.h>
#include <string.h>

#define LEFT(x) ((x) << 1)
#define RIGHT(x) (((x) << 1) + 1)

struct node_t {
int left, right;
unsigned colors;
} k[410000];

/**
* @brief 构建线段树
* @param root
* @param left
* @param right
*/
void build(int root, int left, int right)
{
k[root].left  = left;
k[root].right = right;

if (left >= right) {
return;
}

int mid = (left + right) >> 1;
build(LEFT(root), left, mid);
build(RIGHT(root), mid + 1, right);
}

/**
* @brief 线段树染色
* @param root
* @param a
* @param b
* @param c
*/
void insert(int root, int a, int b, int c)
{
if (a <= k[root].left && b >= k[root].right)
{
k[root].colors = 1 << (c - 1);
return;
}

if (k[root].colors)
{
k[LEFT(root)].colors  = k[root].colors;
k[RIGHT(root)].colors = k[root].colors;
k[root].colors = 0;
}

int mid = (k[root].left + k[root].right) >> 1;
if (b <= mid) {
insert(LEFT(root), a, b, c);
} else if (a > mid) {
insert(RIGHT(root), a, b, c);
} else {
insert(LEFT(root), a, mid, c);
insert(RIGHT(root), mid + 1, b, c);
}
}

/**
* @brief 查询染色情况
* @param root
* @param a
* @param b
* @return
*/
unsigned search(int root, int a, int b)
{
if (k[root].colors) {
return k[root].colors;
}

int mid = (k[root].left + k[root].right) >> 1;

if (b <= mid) {
return search(LEFT(root), a, b);
} else if (a > mid) {
return search(RIGHT(root), a, b);
} else {
unsigned int c1 = search(LEFT(root), a, mid);
unsigned int c2 = search(RIGHT(root), mid + 1, b);
return c1 | c2;
}
}

/**
* @brief 交换
* @param a
* @param b
*/
void swap(int &a, int &b)
{
int tmp = a;
a = b;
b = tmp;
}

int main(int argc, char *argv[])
{
int l, t, o;
scanf("%d%d%d", &l, &t, &o);

build(1, 1, l);
insert(1, 1, l, 1);

while (o--)
{
char op[2];
scanf("%s", op);

if (strcmp(op, "C") == 0)
{
int a, b, c;
scanf("%d%d%d", &a, &b, &c);

if (a > b) {
swap(a, b);
}
insert(1, a, b, c);
}
else if (strcmp(op, "P") == 0)
{
int a, b;
scanf("%d%d", &a, &b);

if (a > b) {
swap(a, b);
}
unsigned colors = search(1, a, b);
int count = 0;
while (colors)
{
if (colors & 1) {
++count;
}
colors = colors >> 1;
}

printf("%d\n", count);
}
}
return 0;
}